At roadway maintenance and construction sites it is common practice to use conical markers, signs, flags, flashing lights, etc. to warn motorists of a traffic diversion ahead and to direct traffic away from the maintenance or construction area. In addition, particularly on high speed throughways and at other locations where there is a danger that work crews may be injured by motorists who disregard or fail to observe these warnings, temporary traffic barriers have been set up in an attempt to positively prevent an errant vehicle from reaching the maintenance and construction area. Wooden or concrete barriers have been used at long term projects, while generally at projects of short duration a heavy piece of mobile equipment such as a large truck has been positioned on the roadway between the work crew and the oncoming traffic. In some cases the truck has been equipped with a crash cushion to reduce the severity of impact to the errant vehicle, and its occupants as well as to the truck and the work crew. In some situations crash cushions are placed directly on the roadway to serve as a cushioning device.
The various traffic barriers and installation procedures employed heretofore have exhibited a number of disadvantages. In cases in which wooden barriers were used, they had a tendency to splinter on impact, and the splinters on occasion would create a hazard by piercing the vehicle and thus seriously injuring the occupants. Concrete barriers, due to their weight and size are time consuming to transport, install, remove and relocate and therefore are not practical for short duration work operations or for low speed roadway conditions. In addition, these types of positive barriers can themselves constitute a roadside hazard to errant vehicles.
The use of a heavy construction vehicle as a barrier had the disadvantage that an expensive or special purpose piece of equipment was tied up and unavailable for other purposes for the duration of the work project. In the event of an accident the equipment was vulnerable to extensive damage rendering it out of service and subject to costly repairs and/or replacements.
In situations where crash cushions were placed directly on the surface of the roadway, the transporation, installation and removal of such devices was a time consuming task. In the case of vehicle mounted crash cushions, such as; liquid filled cells, light-weight concrete cells, and synthetic foam cartridges; a strong, fixed backup and support structure, mounted to a heavy vehicle is required for these cushioning devices.